Executive brief
A security vulnerability exists in the ToToLink A720R router, a device used to provide wireless internet connectivity. An attacker with the ability to modify local system files could trigger a crash or potentially take control of the device's operating system. This could lead to a complete disruption of internet services or unauthorized access to the router's internal functions.
Technical details
A stack-based buffer overflow exists in the 'sysconf' binary of the ToToLink A720R router (firmware V4.1.5cu.614_B20230630) within the sub_401EE0 function. The vulnerability is caused by the unsafe use of sscanf() with a %s format specifier when parsing data read from /proc/stat via fgets(). Specifically, the binary attempts to write string data into a single-byte char variable (v23), leading to an overflow of adjacent stack memory. An attacker with local filesystem write privileges or the ability to influence the contents of /proc/stat can exploit this to overwrite the return address and achieve arbitrary code execution.
Affected products
- ToToLink A720R Router firmware V4.1.5cu.614_B20230630
Timeline
- 2025-11-13: disclosed: Initial disclosure of CVE-2025-60685
- 2025-11-13: advisory